The Duchess of Cambridge wearing the cream Roland Mouret dress TO Claridge's in May 2012. Photo: Rex

Designer Roland Mouret has revealed that the Duchess of Cambridge specifically asked that the cream gown she wore last year be cut looser than the sample because "she doesn't want a bottom situation like Pippa had."

The French designer revealed the request in an interview published in the February issue of British
Vogue
which questions the much-publicised 'Kate Effect' - the notion that the Duchess' outfit choices have boosted sales for the brands she wears.

On the contrary, Mouret explains that his sales are much more likely to be boosted by someone like Kim Kardashian wearing one of his designs, commenting that "the kind of people who like Kate's style are not the kind to rush out and copy her dress."

Similarly, Jane Shepherdson, CEO of Whistles, pointed out that by the time the Duchess wears one of their pieces, it has most likely already sold out due the their short stock runs. Likewise, the Duchess' decision to wear a Reiss dress for her official engagement photos had little effect on the high-street chain's sales as it was an old style.